Interaction flow method for many-fermion systems

TL;DR

This paper introduces an interaction flow scheme for many-fermion systems that combines renormalization group advantages with perturbation simplicity, demonstrating its effectiveness on 1D fermions and the 2D Hubbard model.

Contribution

It presents a novel interaction flow method that efficiently sums perturbation series, bridging renormalization group and perturbation theory for many-fermion systems.

Findings

Agreement with previous one-loop RG results at low temperatures

Effective analysis of momentum-dependent interactions in the 2D Hubbard model

Applicable to both one-dimensional and two-dimensional fermion systems

Abstract

We propose an interaction flow scheme that sums up the perturbation expansion of many-particle systems by successively increasing the interaction strength. It combines the unbiasedness of renormalization group methods with the simplicity of straight-forward perturbation theory. Applying the scheme to fermions in one dimension and to the two-dimensional Hubbard model we find that at one-loop level and low temperatures there is ample agreement with previous one-loop renormalization group approaches. We furthermore present results for the momentum-dependence of spin, charge and pairing interactions in the two-dimensional Hubbard model.